Process for the preparation of aryl esters of N-alkyl carbamic acids

Abstract

The invention relates to a process for the preparation of aryl esters of N-alkyl carbamic acids. The process comprises reacting an alkyl N-alkyl carbamate of the general formula: R.sub.1 --NH--COO--R.sub.3 wherein R 1 and R 3 are both alkyl groups, with a substituted phenol in the presence of a halogen-containing phosphorous compound to produce an aryl ester of N-alkyl carbamic acid having the general formula: R.sub.1 --NH--COO--R.sub.2 wherein R 1 is an alkyl group and R 2 is an aryl group derived from the substituted phenol. In a preferred embodiment of the invention, the process is used for the preparation of aryl esters of N-methyl carbamic acid.

We claim: 
     
       1. A process for the preparation of aryl esters of N-alkyl carbamic acids, said esters having the general formula:   R.sub.1 --NH--COOR.sub.2     wherein R 1  is an alkyl group and R 2  is an aryl group which comprises reacting an alkyl N-alkyl carbamate of the general formula:     R.sub.1 --NH--COO--R.sub.3     wherein R 1  and R 3  are both alkyl groups, with a substituted phenol in the presence of a halogen-containing of phosphorous compound selected from the group consisting of phosphoryl chloride, phosphorous tribromide and phosphorus pentachloride, the R 2  aryl group being derived from the substituted phenol reactant.   
     
     
       2. A process as claimed in claim 1 wherein R 1  is methyl or ethyl, said alkyl N-alkyl carbamate being correspondingly either methyl N-methyl carbamate or ethyl N-methyl carbamate. 
     
     
       3. A process as claimed in claim 1 wherein said substituted phenol is phenol substituted with from one to three substituent groups equal to or different from one another, said substituent groups being selected from alkyl, alkoxy, alkylthio, alkylamino, alkoxyalkylene, alkylthioalkylene and alkylaminoalkylene groups wherein the alkyl group is a straight or branched group containing from 1 to 5 carbon atoms and the alkylene group contains from one to two carbon atoms; 2,3-dihydro-2,2-dimethylbenzofuran-7-ol; 2,2-dimethyl-1,3-benzo-dioxol-4-ol; 2-(1,3-dioxolan-2-yl)-phenol; 1-naphthol or 2-naphthol. 
     
     
       4. A process as claimed in claim 1 wherein the R 2  aryl group is selected from 2-sec-butylphenyl, 2-isoprpoxyphenyl, 2-isopropylphenyl, 1-naphthyl and 2,3-dihydro-2,2-dimethyl-7-benzofuranyl. 
     
     
       5. A process as claimed in claim 1 wherein the halogen-containing phosphorus compound is phosphoryl chloride. 
     
     
       6. A process as claimed in claim 1 wherein said reaction is effected at a temperature in the range of from 0° C. to 150° C. 
     
     
       7. A process as claimed in claim 1 wherein the reaction is effected in the presence of a solvent selected from the group consisting of benzene, toluene, xylene and chlorohydrocarbon solvents. 
     
     
       8. A process as claimed in claim 1 wherein the reaction is discontinued by quenching the reaction product in water.